An herbicide is a compound which adversely controls or modifies plant growth, e.g., killing, retarding, defoliating, desiccating, bleaching, regulating, stunting, tillering, stimulating and dwarfing and otherwise adversely alter physiological plant processes. The term "plant" refers to all physical parts of a plant, including seeds, seedlings, saplings, roots, tubers, stems, stalks, foliage, and fruits. "Plant growth" includes all phases of development from seed germination to natural or induced cessation of life.
Herbicides are generally used to control or eradicate weed pests. They have gained a high degree of commercial success because it has been shown that such control can increase crop yield and reduce harvesting costs when weeds are not present in the field to complicate and reduce yield.
The most popular methods of herbicide application include: pre-plant incorporation into the soil; in-furrow application to seeds and surrounding soil; pre-emergence surface treatment of seeded soil; post-emergence treatment of the emerged and growing plant and soil; and pre-plant seed treatment. The preferred method of application is the post-emergence method whereby contact, translocation and residual herbicidal activity are in effect.
A manufacturer of an herbicide generally recommends a range of application rates and concentrations calculated to maximize weed control. The range of rates varies from approximately 0.01 to 50 pounds per acre (0.0111 to 56 kilograms per hectare [Kg/ha]), and is usually in the range of from 0.1 to 25 pounds per acre (0.112 to 28 Kg/ha). The term "herbicidally effective amount" describes an amount of an herbicide compound which adversely controls or modifies plant growth. The actual amount used depends upon several considerations, including particular weed susceptibility and overall cost limitations.
An important factor influencing the usefulness of a given herbicide is its selectivity towards crops. In some cases, a beneficial crop is susceptible to the effects of the herbicide. In addition, certain herbicidal compounds are phytotoxic to some weed species but not to others. To be effective, an herbicide must cause minimal damage (preferably no damage) to the beneficial crop while maximizing damage to weed species which infest the locus of the crop.
To preserve the beneficial aspects of herbicide use and to minimize crop damage, many herbicide antidotes have been prepared. These antidotes reduce or eliminate damage to the crop without substantially impairing the damaging effect of the herbicide on weed species. See, for example, U.S. Pat. Nos. 4,021,224, 4,021,229 and 4,230,874.
The precise mechanism by which an antidote reduces herbicidal crop injury has not been established. An antidote compound may be a remedy, interferent, protectant, or antagonist. As used herein, "antidote" describes a compound which has the effect of establishing herbicide selectivity, i.e., continue herbicidal phytotoxicity to weed species by the herbicide, and reduced or non-phytotoxicity to the cultivated crop species. The term "antidotally effective amount" describes an amount of an antidote compound which counteracts to some degree a phytotoxic response of a beneficial crop to an herbicide.
Acylated 1,3-dicarbonyl compounds have been found to be very effective herbicides with broad general herbicidal activity against a wide range of plant species. The method of controlling vegetation with the compounds comprises applying an herbicidally effective amount of the compounds, usually with an inert carrier, to the area where herbicidal control is desired. However, the herbicidal acylated 1,3-dicarbonyl compounds have been found in some instances to adversely affect or interfere with the cultivation of a variety of crops. Therefore, the effective use of these herbicides for controlling weeds in the presence of such crops is further enhanced by, or may require in many instances, the addition of an antidotally effective amount of a compound, which is antidotally effective with the herbicide.